Fluid-filled cylinders are used in various industries such as the medical, pharmaceutical and chemical industries for containing fluid in the form of gas or liquid under compression. These cylinders can be designed for one-time use or for re-use. The present invention is concerned primarily with refillable and reusable cylinders.
Known refillable cylinders are commonly made of metal, such as steel or aluminium, and painted either for cosmetic reasons or to comply with industry norms for identification of the fluid contents. For example, in Canada, oxygen-containing cylinders are painted a standard white colour, while in the United States they are painted a standard green colour. Other product information, some of which is mandatory, is printed on labels affixed to the cylinders.
When these cylinders are emptied, they can either be refilled with the same substance or a different substance altogether. In the case of the latter, relabelling is required and it may be necessary to paint the cylinders a different colour to indicate the new substance.
When refilled with the same substance, no repainting or relabelling is required. However, over time and with handling, there is a tendency for the paints and labels to peel off or exhibit other wear characteristics such as scratches and fading. Further, metal cylinders may rust due to exposure to the elements. For many cylinder companies which sell fluid-filled cylinders and refill emptied cylinders, the look of the cylinder is an important feature of the product. Consequently, many cylinder companies have adopted a policy of repainting and relabelling emptied cylinders every time they are returned by customers for re-filling. The associated costs of cylinder maintenance are therefore quite substantial.
An object of the invention is therefore to provide a new and improved method of protecting the outer surface of cylinders for containing fluids against wear and exposure in order to maintain their aesthetic appeal while reducing maintenance costs.